I got off Sanet last Spring, but after reading the web archives on
brown rot of peaches it sparked my interest to temporarily rejoin
and add a few observations and resources.
Observations on Climate and Organic Peach Orcharding:
Climate, and very specifically humidity, plays is a huge factor
in the occurence of brown rot on peaches.
Peach farmers in the Humid East wake up in the morning with three
strikes against them in comparison to their Western neighbors.
As you travel West, driving into the Short Grass Prairie
regions of Westen Texas-Oklahoma-Kansas northwards, you
enter the realm of possibilities. By the time you reach
the Front Range of the Rockies in Colorado, you enter the zone
of reality... with respect to dry air and brown rot on peaches.
During the summer months here in Arkansas, it is not uncommon
to experience 98% relative humidity. If you watch the national
weather maps, the dewpoint average is very high in the
southeastern U.S. Locations like Little Rock, AR, Atlanta, GA,
and Houston, TX are very typically the highest in the nation.
By contrast, California growers enjoy two unique climactic zones
that enable organic peach orcharding to take place: the
Mediterranean Climate which has a dry growing season and winter
precipitation, and the Desert Climate, which has a Mediterranean
rainfall pattern but very low overall precipitation.
Last week I returned from a California trip that included a seminar
at an organic peach orchard and a tour of a conventional peach
orchard.
As an example, while the conventional orchard uses herbicides for
weed control, insecticides for mites and insects, fungicide in
the post-harvest wax, commercial fertilizers injected
into drip irrigation, and poisons for gophers... they do not use
*any* fungicides in their foliar spray program. The reason being is
that air is so dry in the desert valley that diseases are practically
non-exisitent. A few peaches will still get brown rot, but they are
merely picked off and tossed aside.
[By comparison, practices at the organic peach orchard: soil applied
compost, microjet irrigation, Brix Mix from Peaceful Valley Supply as
a foliar spray, hand weeding to control vegetation, cover crops sown
in October -- with some reseeding by subclover, Tanglefoot applied to
trunks to trap ants climing into trees to herd aphids, twin rows of
eggplant raised in the alleyways between peach trees as an intercrop]
Thus, "where" you live makes a HUGE difference with respect to
brown rot on peaches.
Future Tools:
The following tools -- when they become available -- could
result in a dramatic shift in low-spray and organic peach
orcharding. However, they are still in research stages:
*Biocontrol for brown rot as an orchard spray for protection
during the growing season.
*Biocontrol for brown rot for protection during post-harvest
shelf life
When you look at this picture, it really does strike home that
certain tools such as biopesticides really do and will make an impact
on the feasibility for organic and low-spray production systems.
Plain Organics vs Sophisticated Organics:
To the extent that farmers or researchers will attempt to push the
envelope and grow organic peaches in the Humid East, in my estimation
it would helpful to emphasize sophisticated organics over plain
organics.
Plain organics can be characterized by early transition organic
farming and by the substitution method. For example, where
Extenion Service fertililizer recommendations call for so many pounds
of fertilizer per acre, simply calculate how much fertilizer can be
obtained from organic fertilizers and composts using linear
conversions. If diseases are a problem, spray sulfur... because
that is what is listed as an alternative fungicide.
Sophisticiated organics include:
*humus management practices (cover crops, composts, microbials) that
enable shifts in quality of soil humus and the soil foodweb for whole
plant systemic resistance to disease
*foliar feeding practices that influence the phyllosphere; e.g.,
compost teas, rock dusts, hydrogen peroxide, humates, microbials,
biosimulants and use of refractometers to measure leaf sap as well as
fruit sap brix
*energetic tools: radionics, cosmic pipes, biodynamic preparations,
water treatments
Resources:
Organic Control of Peach Brown Rot in California, USA
http://www.agroecology.org/cases/brownrot.htm
Peach Brown Rot Study at Woodleaf Farm, Oroville, CA in 1993
http://www.agroecology.org/cases/brownrot/studies.htm
These web links (which refer to Carl Rosato's on-farm research
with organic peach orcharding in Oroville, CA) are examples of case
studies on the very informative Agroecology website.
Certainly, the foliar sprays Carl is using are examples of
sophisticated organics. In fact, Rosato is a pioneer in the
preparation and use of compost teas.
Still, with respect to climate you can see that a grower like Carl
Rosato in California has a destinctly unique advantage in comparison
to a grower in the eastern U.S.
Finally, I am reminded of the $100 reward Michael Maltus (then
living in the Missouri Ozarks before migrating to California
for greener pastures) offered for several years in the mid 1980s to
anybody in the Eastern U.S. (including the NAFEX crowd of
experimental growers) who could show they raised organic
apples on a commercial basis (at least 100 trees)... yet nobody ever
took him up on that reward, due to the arch nemisis of organic apple
orcharding, the plum curculio.
Likewise, do any commercial orchards in the Humid East actually
produce organic peaches? If so, how do they do that?
Steve Diver
ATTRA
http://www.attra.org
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